"Rational" humans who try to lead lives as fancy computers that can be reprogrammed at will too easily crack under the strain. Strain of what? Perhaps the strain of trying to liberate oneself too fully from the very roots of human construction.
"I see no reason to doubt that humans have at least evolved a capacity to live "beyond claw and tooth", but this will be most likely (my personal religion) if we acknowledge, rather than deny, the claws and teeth of our psychological heritage."
I could not agree more. In fact I suspect many of our social problems stem from the over utilization of one characteristic (acquisativeness) at the expense of another (e.g. compassion or sharing).
But I was reminded of something someone mentioned to me the other day. He said that Pure Intellect is incapable of deciding anything! A Vulcan planet of Spocks would be quite impossible. One can imagine an asteroid hurtling toward the planet while computor brains calculate trajectories, inertial force, and moment of impact - but do nothing. Why? because such decisions are not value free, and I submit that values (as well as ethics) are emotionally derived.
Somebody (was it Marx?) said that the proper study of mankind is man. Understanding why we are the way we are seems critically important in this period of history when our impact on our environment has become so consequential. Nor should understanding in any way diminish amazement at the entire process, for me it only enhances.